Header, Intake, & Exhaust - Newbie: intake effect on mileage

Hi gang . My first post about my first Civic, an '06 EX Coupe 5-speed. What [if any] effect does a CAI have on gas mileage? I did an archive search but didn't find anything. Thanks

With an intake, you'll actually see better gas mileage.

i have a 93 dx with a 1.5 with a short ram i gained almost 2 mpg

i think forty was running in the high 30s, low 40s on the higway with a CAI and aftermarket exhaust...dotn quote me on it tho.

When you say "aftermarket exhaust" do you mean cat-back? What's the difference between cat-back and axles-back? Does just adding a muffler [DC Sports] add any power, or just a nicer tone. It looks like my budget is going to cover an AEM CAI and a muffler.
ORIGINAL: Nail I3unny

i think forty was running in the high 30s, low 40s on the higway with a CAI and aftermarket exhaust...dotn quote me on it tho.

cat backs are all the piping from the catalytic converter back...cat..back...get it?

axle backs are just that...from the axle back. its basically the B-pipe and muffler of a catback. they wont add any performance.

a muffler wont do anything to your car except make it sound like enormous asshole.

but unless your running a pretty modded engine a cat-back doesn't add much performance either. cat-backs sound worse than an axle-back because you retain the stock resonator. cat-backs lose more in the bottom end...they dog more

Let me see if I've got this straight. A CAI adds power, performance and sound. Adding any exhaust short of a header adds nothing else but noise if the motor is stock, right? I'm an old guy [44] who just wants a little more power and would like to hear it. I won't be swapping in a K20 [I have no idea what I just said] and dropping it 3 inches....yet!

it will too add power. its one of the first things anyone ever changes on their car for the moderate gain at a fairly cheap price.

4-2-1 and 4-1 headers are the two basic designs.

a 4-2-1 (also known as a 'tri-y') takes the four exhaust ports, converges it into two pipes, than converges the two pipes into one...like this:
http://www.modacar.com/Merchant2/headers_honda_files/apexi_header.jpg

a 4-1 takes the four and converges them down into one pipe all at once..like this:
http://www.modacar.com/Merchant2/headers_honda_files/dc_41_ceramic_header.jpg

normally (doesnt always apply...), a 4-2-1 header will give you more low-mid range power. a 4-1 header will give you top end power. general consensus is 4-2-1 is for autocrossing adn street driving and 4-1 is for drag racing.

exhausts will add more power than an intake or header...usually about 4-8. they basically make flow less restricted...so its like blowing through a coffee straw (stock exhaust) vs. blowing through a mcdonalds straw (aftermarket exhaust). one thing you wanna be careful of tho is you dont want to go too big...because then you can lose exhaust velocity and actually lose power. its like blwoing through a paper towel roll...only not quite that extreme...

a K20 is a honda engine...and one helluva sweet one too.

dont drop it 3 inches...ever :p.

ORIGINAL: Nail I3unny

i think forty was running in the high 30s, low 40s on the higway with a CAI and aftermarket exhaust...dotn quote me on it tho.


yup, 38.6mpg average, and that was with a few really good 60-90 pull passes on the two lane highway. AEM CAI, stock header/dp/cat, and Megan Racing 2.5" cat-back on a 56k mi engine. I know I could have hit 40mpg if I could keep myself from getting on it so hard :D

Mine routinely did 40 MPG, so I got to see what it does now with this new intake...

a cat back on a stock motor will loose some low end power but you will gain a good bit on the top end. it also can sound liike **** because you would be cutting out a resinator, but the higher-end systems come with a resinator in its place and really make a difference in sound. ill find a sound clip of my beast when it was just stock with a skunk2 catback...

http://media.putfile.com/01-civic-ex-with-skunk2-catback

here it is ^ enjoy

Just remember to keep the filter clean on the intake...that way, you get the most MPG. The cleaner the filter, the better MPG.

i just installed a cai and have not noticed a change in mpg. that might be because i keep flooring it though. :D

Form what I can see, MPG goes up if you are driving for ecnomy, but if you put the boot down, it's gonna lose MPG.

It's also going to wake up the neighborhood.

So will adding a DC Sports muffler add more power over just the CAI, or do I need cat-back or axle-back to get a result. I'm still confused about the cat- and axle. The cat seems to be at the front axles. What's between the cat and the axle-back if you mount an axle-back? Sorry if this sounds lame. My last car was a Porsche Boxster S. The freakin thing was already so fast I never bothered to modify it. Besides, I spent all my money repairing it!

ORIGINAL: Nail I3unny

it will too add power. its one of the first things anyone ever changes on their car for the moderate gain at a fairly cheap price.

4-2-1 and 4-1 headers are the two basic designs.

a 4-2-1 (also known as a 'tri-y') takes the four exhaust ports, converges it into two pipes, than converges the two pipes into one...like this:
http://www.modacar.com/Merchant2/headers_honda_files/apexi_header.jpg

a 4-1 takes the four and converges them down into one pipe all at once..like this:
http://www.modacar.com/Merchant2/headers_honda_files/dc_41_ceramic_header.jpg

normally (doesnt always apply...), a 4-2-1 header will give you more low-mid range power. a 4-1 header will give you top end power. general consensus is 4-2-1 is for autocrossing adn street driving and 4-1 is for drag racing.

exhausts will add more power than an intake or header...usually about 4-8. they basically make flow less restricted...so its like blowing through a coffee straw (stock exhaust) vs. blowing through a mcdonalds straw (aftermarket exhaust). one thing you wanna be careful of tho is you dont want to go too big...because then you can lose exhaust velocity and actually lose power. its like blwoing through a paper towel roll...only not quite that extreme...

a K20 is a honda engine...and one helluva sweet one too.

dont drop it 3 inches...ever :p.



So if i wanted to buy a 4-2-1 header , what exactly are you looking for, are they similar to the filters in that they all basically do the same thing, so just buy the cheapest one?

not really. you want to get a decent quality one (IE Megan Racing or DC Sports) but dont pay too much for it. some ebay manifolds (XS Power, SSAutochrome) have been known to crack welds fairly quickly...theyre mostly hit and miss.

not all air filters are created equal.

ORIGINAL: Remi

So will adding a DC Sports muffler add more power over just the CAI, or do I need cat-back or axle-back to get a result. I'm still confused about the cat- and axle. The cat seems to be at the front axles. What's between the cat and the axle-back if you mount an axle-back? Sorry if this sounds lame. My last car was a Porsche Boxster S. The freakin thing was already so fast I never bothered to modify it. Besides, I spent all my money repairing it!


Mufflers are only good for one thing, making you louder. Axlebacks, pretty much the same story. When you hear "cat-back," it simply means that the exhaust pieces will start just after the Catalytic Converter, and go all the way back to the tip. A cat-back is definitely what you want to look for.

Thanks for all your advice. The AEM CAI's in the mail! I don't have the bucks for a full cat-back right now, and the muffler just sounds like a noise maker so I blew that off. I'll let you know what I think of it when I get it installed. I doubt many people have one on an '06 single cam yet. I was leaning toward the gray one 'cause it's not an Si, the car's gray, and I'm not 20 years old. Couldn't do it. It's red.

Glad to hear you went with the AEM CAI, you wont be disappointed.

Keep us posted on progress!!

from waht ive heard a CAI on the 06 is a tough install. or at least it takes some patience. let us know how it goes!

I'm too lazt to link you, but I made a post on here a while back with some informative links about exhaust design.

As for the intake, I would think a short ram would provide better gas milegae than a CAI. Hot air atomizes fuel better. I might be wrong on that though.